Lsi Logic Corporation

Matthew C Muresan

Jackson L Ellis

Graeme M Weston-Lewis

Richard Martin Born

In a data processing system having few initiators or several initiators with the same parameters, support for all initiators is provided by storing sets of parameters and corresponding lists of initiator IDs in cache entries. Based on the initiator ID in a selection command, the target selects the appropriate parameters and automatically transitions to data transfer mode. Low cost support for all initiators is thus provided.

Method to store initiator information for SCSI data transfer

A method and apparatus for writing data to a storage device such as a hard disk drive in which two write commands from an initiator are processed as a single command at the storage device. A first request is received from a small computer systems interface (SCSI) bus to write a first set of data to a storage device. The first set of data is transferred to memory for temporary storage prior to transfer to the storage device. Thereafter, a second write request is received to write a second set of data to the storage device in which the write request includes a logical block address. An ending logical block address determined after transferring the first set of data is compared to the logical block address of the second request to determine whether the second set of data can be written to the storage device along with the first set of data as a single write operation based on the comparison of the logical block address of the second request and the ending logical block address. In response to a determination that the first set of data and the second set of data can be written to the disk as a single write operation, the second set of data is written to the memory as a part of the first write request. The second set of data may be automatically transferred to the memory, to be written to the storage device as a second write operation in response to a determination that the first set of data and the second set of data cannot be written as a single write operation.

Method and apparatus having automated write data transfer with optional

In a SCSI controller, unexpected messages are automatically received in response to an attention signal by receiving all of the bytes constituting the message and storing those bytes in an available register file selected from a plurality of register files in the controller. Once the entire message has been received and stored, a determination of an appropriate response is initiated. The register files are also used to hold selection information during a bus-initiated selection, so additional architecture is not required.

Method to handle SCSI messages as a target

A circuit for embedding within a SCSI control device for generating REQ or ACK signals in a flexible manner as required for SCSI synchronous data transfer mode. The circuit of the present invention utilizes a single counter and associated logic to provide flexible waveform generation of the REQ or ACK signal in a SCSI control device. The counter value counts up from zero and is compared against one of two values applied to a comparator. The first value is the desired period (duration) of the assertion of the REQ/ACK signal. When this count value is reached, the counter is restarted, the REQ/ACK signal is de-asserted, and the second count value--the de-assertion time--is applied to the comparator. When the second count is reached, the cycle starts over. An enable and reset signal allow other portions of the SCSI control device to start, stop, and reset the counter circuit of the present invention as required for SCSI synchronous data transfer controls. An alternative embodiment of the invention utilizes a down counter circuit which may embed a comparison against zero thereby obviating the need for a separate comparator circuit. The waveform generated may be applied to either the REQ signal in a target mode of the SCSI device or to the ACK signal in the initiator mode of the SCSI device.

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Fort Collins, CO, United States of America

Matthew C Muresan